1. Field of the Invention
The present invention relates to a recording and reproducing apparatus, and particularly to a digital video cassette recorder (VCR).
2. Description of the Prior Art
Most VCRs available today using analog recording, but the image deterioration resulting during recording, reproducing, and particularly dubbing with analog VCRs has heightened interest in digital recording VCRs.
An example of a common consumer digital VCR is described in the ICCE Digest of Technical Papers, June 1989, 6-9.
VCRs today also use helical recording, a recording/reproducing method whereby heads are mounted on a cylinder positioned at an angle to the perpendicular and rotating at high speed, and the magnetic tape is transported while wrapped by a loading post to the cylinder.
Tracks are recorded in this helical recording method by the movement of the magnetic tape and the rotation of the heads.
The recorded television signal is often compressed to reduce the amount of data recorded. Intra-frame compression is generally used for the video signal due in order to enable image editing, but inter-frame compression methods, which obtain the difference between the current intra-frame compressed image and the images before and after, have been recently established (e.g., MPEG compression).
The conventional recording method described above, however, cannot be easily applied to recording and reproducing inter-frame compressed video signals. For example, significant image degradation occurs when errors occur during reproduction. More specifically, in coding methods using inter-frame compression, if the current image (frame) (the image referenced to obtain the difference from the before and after images) is disrupted, the deterioration in image quality will extend across several following frames; if the intra-frame compressed area is disrupted due to a signal error, the frames interpolated based on that image area will be severely disrupted.
Gaps may also appear in the data when an error occurs during reproduction and during high-speed reproduction, and data duplication may occur during slow reproduction modes and when reproducing tapes to which the data is recorded plural times.
The data compression decoder is able to decode and reproduce the signal during normal reproduction modes, but is unable to function normally during high-speed reproduction and when data is lost or duplicated due to an error, and in the worst case scenario may not be able to decode the video signal.